Dimorphic expression of cerebrosides in the mycopathogen Sporothrix schenckii

Major neutral glycosphingolipid components were extracted from Sporothrix s chenckii, a dimorphic fungus exhibiting a hyphal saprophytic phase and a ye ast parasitic phase responsible for chronic mycotic infections in mammalian hosts. These components, one from the mycelial form and two from the yeast form, were purified and their structures were elucidated by H-1 nuclear ma gnetic resonance (NMR) spectroscopy, electrospray ionization mass spectrome try (ESI-MS), and tandem ESI-MS/MS, All three were characterized as cerebro sides (monohexosylceramides) containing (4E, 8E)-9-methyl-4,8-sphingadienin e as the long-chain base attached to N-2'-hydroxyoctadecanoate and N2'-hydr oxy-(E)-Delta(3)-octadecenoate as the fatty acyl components. However, while the mycelial form expressed only beta-glucopyranosylceramide, the yeast fo rm expressed both beta-gluco- and beta-galactopyranosylceramides in approxi mately equal amounts. In addition, while the glucosylceramides of both myce lial and yeast forms had similar proportions of saturated and (E)-Delta(3) unsaturated 2-hydroxy fatty acid, the galactocerebroside of the yeast form had significantly higher levels of (E)Delta(3) unsaturation. The difference s in cerebroside hexose structure represent a novel type of glycosphingolip id dimorphism not previously reported in fungi, Possible implications of th ese findings with respect to regulation of morphological transitions in S, schenckii and other dimorphic fungi are discussed. Dimorphic expression of cerebrosides in the mycopathogen Sporothrix schenckii.